Unit 6 · The Internet & Computing Systems · Lesson 6.11

The Web on Top of the Internet

The internet and the web are not the same thing, and after today you can explain the difference. Most adults can’t. Then: the photo trip from Day 1, every arrow finally labeled.

Big Idea 4 — Computer Systems & NetworksCED 4.1 · the photo-trip payoff

Before this lesson — read on Runestone

20.2.3 Systems Built on the Internet

Ten minutes. Read it before class; we start from it. Enrolled in our Runestone course? Open it from there so your progress counts.

Where We Are

People→ Bits→ Programs→ Internet→ Security→ Big Data→ Impact

Internet, top layer. Everything from 6.1–6.10 runs underneath every web page you’ve ever loaded. Today you see it all at once.

The Hook

Internet ≠ web. Email isn’t the web. A video-call app isn’t the web. Your game’s online mode isn’t the web. All of them use the internet.

So what is the web, exactly?

The Idea

The internet is the network: devices, routers, cables, and the protocols (IP, TCP) that move packets. The World Wide Web is one system that runs on top of it: a huge collection of linked pages, files, and programs, reached with a browser.

Piece of the web	Its job
URL	the address of one page or file: https://photos.example.com/trip.html
HTTP	the protocol the web uses: the browser sends a request, the server sends a response
HTTPS	HTTP with encryption, so others on the path can’t read it (Unit 7)
HTML	the format of the page itself — text, links, and where images go
client / server	your browser asks (client); the computer holding the page answers (server)

One page is many requests. The HTML arrives first, then the browser requests every image, font, script, and style sheet it mentions — often dozens or hundreds of separate HTTP requests. Each one is DNS, TCP, packets, and routing all over again.

Your teacher will open the browser’s developer tools (Network tab) on a news site and count the requests. If developer tools are blocked on your Chromebook, watch the projector.

Try It — The Whole Trip, Then Sort It

Part 1. Step through what happens after you tap a link. Every step is a lesson from this unit.

Part 2. Is it the web, or the internet but not the web?

Vocabulary

World Wide Web Internet: A system of linked pages, programs, and files, accessed with a browser. It runs on the internet; it isn’t the internet.
HTTP Internet: HyperText Transfer Protocol. The protocol the web uses: a client requests, a server responds.
HTTPS Internet: HTTP with encryption. Preview of Unit 7.
URL Internet: Uniform Resource Locator. The address of a specific page or file on the web.
client Internet: The device or program that requests data — usually your browser.
server Internet: The computer that stores data and sends it when a client requests it.

Check

Five questions. Internet vs. web is the one people miss.

0 of 5 answered

Impact Check

Free pages, paid for by watching

Many of the requests a news page makes aren’t for the news. They go to ad and tracking companies, which learn which page you read. That’s a big part of how “free” sites pay for themselves — and it’s the metadata lesson (5.2) running on every page load.

Connections

Came from 0.1 — the photo trip. Put your Day-1 board photo next to Part 1 — every arrow now has a name.

Came from 6.2 — HTTP is the application layer. It trusts TCP and IP and ignores how they work.

Next in 6.12 — you measure the network this all runs on: latency, hops, and speedup.

Opens Unit 7 — HTTPS. Everything that travels can be intercepted — next unit’s whole premise.